1. Technical Field of the Invention
The present invention relates, generally, to the provision of a wide area, long distance bulk electric power transmission system.
More particularly, the present invention pertains to, and defines, a transmission system dedicated entirely to the transmission of electric power derived solely from renewable resources and a method of managing such energy on a sustainable basis for delivery to territorially based utilities.
2. Description of the Prior Art
The electricity market in the United States for the year 2005 exceeded four trillion kilowatt hours representing revenues exceeding $300 billion (U.S. dollars.) A substantial majority of that electricity is generated using fossil fuels as the initial source of energy. Coal, s fossil fuel, alone amounts to almost 50% of the total energy source; natural gas provides almost another 19% and nuclear energy also about 19%. Energy from hydroelectric sources is approximately 6.5% and petroleum amounts to about 3%. The contribution from renewable resources amounts to somewhere between 2.5 and 3%.
According to industry sources, statistics show that electricity consumption will increase by more than 50% by 2025. Hence, assuming no changes in the sources of energy are implemented, current sources of energy must be greatly expanded to meet these expected demands. There are serious problems, however, in expanding the use of the current sources of energy. While the world's supply of coal may seem adequate for the time being, both political and environmental pressures seek to reduce the use of coal in the near future. Among the totality of electricity generating plants, coal fired plants are one of the largest of contributors of greenhouse gas emissions, including not only carbon dioxide, sulfur compounds, oxides of nitrogen, other small amounts of toxic elements, etc. Local and regional jurisdictions have already begun putting limits upon the continued use of coal powered plants. Natural gas also produces oxides of carbon and other pollutants, and as a fossil fuel, has limited resources and increasing costs. Nuclear systems, while clean in operation, are generally unpopular, feared as unsafe by many environmentalists and exceedingly expensive. The problem of dealing with nuclear waste has only been partially dealt with. Finally, there has been an historical decline in the growth of hydroelectric power, as water resources become fractionalized by the increasing tension between agricultural and domestic utilization. Hence, legacy coal and other fossil fuel systems will increasingly go off-line and an increasing percentage of replacement power must therefore be found from other sources.
Currently, many states in the United States have legislated renewable portfolio standards (RPS) which mandate that, at some point in time between 2010-2025, an average of 20 to 25% of all electricity be generated using renewable resources at the point of generation on a blended basis, and this percentage is slated to increase in the near future. A federally mandated RPS is being discussed as well. Hence, market demands, environmental desires and government regulations will each drive demand in the electric industry for the development of feasible and sustainable energy generated from renewable resources; the cost of such renewable resources for energy generation continues to be a major concern.
Existing technologies, which employ renewable resources, include wind generation, solar, geothermal and biomass. Each of these technologies (with the possible exception of biomass), as implemented or contemplated today, cannot provide reliable baseload energy, i.e., each such renewable resource not provide electric energy on a constant nor predictable basis, or at economical market prices. In addition to establishing renewable generation facilities, the transmission and delivery of renewable energy is dependent not only upon reliable sources of such energy to provide predictability, but also upon the availability of transmission line capacity. Renewable source generators are often located depending upon the geographic location of their fuel sources, such as wind belts or solar content, which often is not necessarily conveniently located near power lines or cities needing their power, such that new or additional transmission lines must be constructed. Today's underdeveloped and oversubscribed transmission systems have exacerbated the problem of integrating intermittent renewable energy into the grid.
The problem of how to integrate power from intermittent sources (e.g., wind and solar) with the power from sustained sources (e.g., coal or gas) into the transmission grid can best be understood, at least, in part, from the ensuing explanation: A baseload power plant is one that provides a steady flow of power regardless of total power demand by the grid. These plants run at all times through the year except in the case of repairs or scheduled maintenance. Power plants are designated “baseload” based on their low cost of generation, efficiency and safety at set outputs. Baseload power plants do not change production to match power consumption demands. Generally, these plants are sufficiently large to provide a majority of the power used by a grid. As presently used, coal-fired plants are more efficient, as they can run continuously to cover the power baseload required by the grid. They are slow to fire up and to cool down and are therefore generally run at fairly constant output. Each baseload power plant on a grid is allotted a specific amount of the basic power demand to handle. For a typical power system, a rule of thumb is that baseload power is usually 35-40% of the maximum load during the year.
Natural gas and oil powered plants are much faster to start, but have much higher fuel costs. These plants are generally designed to handle peak power demands, since they can be ready to supply power in 30 minutes or less; they are more expensive to operate than coal power plants, primarily due to higher fuel costs.
Hydroelectric power is the quickest to respond to increasing power demands, reaching full power in about two to three minutes. These plants can provide both base load and peak load demands for power at a relatively low cost, but are limited by the amount of water available, as well as other considerations, such as a fractionalized demand created by the tension between municipal and agricultural needs, the need to limit water discharge for flood control reasons and the many issues created by environmentalists.
A special case of hydroelectric power is “pumped storage,” wherein excess power from base load plants is used to drive pumps that fill an artificial or natural reservoir, usually at higher elevations. When power demand exceeds the ability to provide energy in “real time,” the pumps become generators, feeding the potential energy of the stored water back into the grid, somewhat analogous to a very large storage battery. This same technique has been employed with some wind and/or solar power sources to provide additional power assets available when sun or wind is absent or inadequate.
Certain other types of plants can only be intermittent. Solar and wind power plants generally only produce useful amounts of electricity when conditions are right; their production being totally unrelated to local power demands or needs. When the sun sets or the wind calms, output of solar or wind power plants drop, regardless of the demand for electricity. In addition, the output from wind generators can be quite variable and intermittent, even when some amount of wind is blowing, as wind velocities are seldom constant and changes in velocity and wind direction can vary even within relatively close locales, often resulting in electrical levels that are unacceptable to the grid or at least troublesome to integrate with the output of a baseload generator. This introduces into the discussion the concept known in the power industry as “firming”. Essentially, this concept connotes the integration of intermittent and variable power signals from those sources, with other non-intermittent signals and other electronic regimes, to produce a non-variable, sustainable, constant level signal, i.e., one that is “firm”.
Additionally, presently proposed regimes to integrate renewable power into the grid with baseload generation are hampered by the allocation of transmission “space” on the grid, and by switching from baseload generation to the wind and/or solar sources when they are producing “properly”-either to substitute for baseload power or just to meet increased or peak demand for power above baseload. One difficulty with this regime is mentioned above: These intermittent sources not only produce “unfirmed” power, but they frequently produce power that is almost totally unrelated to actual demand and are therefore unreliable as sources designed entirely to supply peak demands, inasmuch as these renewable power sources lack the ability to provide baseload.
Several schemes have been considered to store the power from these intermittent sources so as to make their power available when, for example, the sun sets or the wind stops, but all are either too expensive or inefficient, and often both. One of the alternatives for storage is mentioned above: The pumping of water uphill into reservoirs and to use the potential energy to generate power on a more “as-needed” basis. Electrical storage batteries and other chemical conversions into storage media, that can be tapped at more convenient times are much discussed in the literature, but none is satisfactorily efficient. As an example, wind power generation has such variability and lack of reliability that many baseload generators are resistant to use it, and will only switch to such sources during their optimum output conditions. Nevertheless, such wind generators, after being switched off the grid, may yet be producing electrical power but are shunted off the grid in order to more conveniently firm the power and to integrate only their rated outputs with the signals from baseload sources.
Among Newton's Laws of Thermodynamics, the First Law deals with the concept of conservation of energy, i.e., total energy is conserved in all processes; none is either created or destroyed. As better explained by Carnot, however, the First Law lacks the ability to account for the effects of friction and dissipation when energy is used in any way. It was the Second Law that recognized this failure and introduced the concept of entropy. Entropy is an expression that accounts for the irreversibility of thermodynamic systems. Whatever system of transformation is chosen, be it mechanical (pumping water uphill and letting it run back down) or chemical (such as changing electricity into chemical form in a battery, and vice versa), requires work, of either a mechanical, electrical or chemical nature, the results of which are irreversible because of entropy. Energy used in the performance of useful work will always be lost either by the heat of friction or in the chemical reactions of the transformation. The loss is irretrievable. Carnot calculated the extent of these losses, however, the exact quantification of them is not deemed necessary for an appreciation of the significance of the present invention.
The lesson of the Second Law of Thermodynamics is that an important goal toward maximum conservation of generated electrical power would be to make as few trans-formations in the form of that energy as possible.
The aforementioned difficulties of integrating the intermittent outputs of renewable systems into baseload systems results in significant inefficiencies in the utilization of renewable resources. Switching “wind-power” on- and off-line, or trying to store the unused output of wind or solar generation, wastes generation assets. It is known, for example, for a “wind farm” containing, perhaps, ten wind generators, that each of the outputs are variable—or at least not identical—however, when those ten outputs are blended into a common collector, some of those variations can averaged out, and become less troublesome. By the same token, the interconnection of geographically disparate wind farms, each experiencing blended, but still variable power signals, can further serve to average out the variables for a collective signal. The same is the case for other intermittent renewable source generators such as solar, wave or tidal sources, including geothermal.
In view of the aforementioned technical difficulties, plus the fact that nationwide, utility providers lack significant renewable generating assets, and that there is a serious shortfall of transmission facilities, which the present invention seeks to significantly mitigate.